Electrostatic separator



M. V. E. HERMAN ELECTROSTATIC SEPARATOR Nov. 17, 1970 3 Sheets-Sheet 1Filed Jan. 29, 1968 Nov. 17, 1970 M. v. E. HERMAN 3,540,191

ELECTROSTATIC SEPARATOR Filed Jan. 29, 1968 3 Sheets-Sheet 2 FIG 3.

Nov. 17, 1970 MTV. E. HERMAN 3,540,191

ELECTROSTATIC SEPARATOR 3 Sheets-Sheet 3 Filed Jan. 29, 1968 UnitedStates Patent O 3,540,191 ELECTROSTATIC SEPARATOR Marc Victor EdgardHerman, 192 Rue Rogier, Brussels, Belgium Filed Jan. 29, 1968, Ser. No.701,318 Claims priority, application Belgium, Jan. 31, 1967,

rm. or. nose 3/74 US. Cl. 55-121 9 Claims ABSTRACT OF THE DISCLOSURE Anelectrostatic separator comprising a pre-ionization zone and anattracting zone, each provided with two sets of electrodes, of which oneset, in the pre-ionization zone, forms the emitting electrodes, each onethereof comprising a thin metal strip laid out in a transverse planewith reference to the direction of flow of the gas to be separated.

The present invention relates to an electrostatic separator comprising apre-ionization zone and an attracting zone, each provided with two setsof electrodes, of which one set, in the pre-ionization Zone, forms theemitting electrodes.

Electrostatic separators are known wherein the emitting electrodescomprise metal filaments; these, generally produced from tungsten,oxidise rapidly and become brittle, which causes disturbances in theoperation of the separator, such as short-circuits calling for stoppagesof the separator in order to replace broken filaments, and the like.

The invention has for its object to overcome this disadvantage. For thatpurpose, in the electrostatic separator according to the invention, eachemitting electrode comprises a thin metal strip laid out in a transverseplane with reference to the direction of flow of the gas to beseparated.

The strips provide in themselves stiffer elements than the filamentspreviously used as emitting electrodes; they are therefore lesssensitive to vibrations during the transport and operation of the dustseparator, the more so as they provide better means of fastening to themembers supporting them.

According to a preferred form of embodiment of the invention, the stripprojects onto a metal surface positioned in a plane substantiallyparallel to the direction of flow of the gas to be separated, whichensures a predominantly unidirectional electron flux because of therepulsion of the electrons produced by the said surface.

Preferably according to the invention the emitting strips are inclinedtowards the attracting zone. This inclination offers the advantage thatthe electrons emitted by corona effect are directed towards the adjacentelectrode of opposite potential, under an angle exceeding 90; thisdisplacement of the electrons causes in turn an air draught through theelectro-separator in the direction of flow of the [gas to be separated.This automatic air draught reduces correspondingly the head lossesusually encountered in electrostatic separators.

According to an advantageous form of embodiment of the invention,between two non emiting electrodes in the preionization zone, isprovided every time a double emitting electrode comprised of a fairlythin, channel-shaped metal section, the legs of which are each providedwith a portion bent towards the adjacent non emitting electrode.

The invention has also for its object a device for the periodicalcleansing of the electrodes of the electrostatic separator permanentlyconnected with the separator device the design of which was favored bythe particular 3,540,191 Patented Nov. 17, 1970 construction of theelectrodes, which are the first object of the present application.According to the invention, the separator comprises cleansing membersextending substan tially parallel to the direction of flow of the gas tobe separated, these cleansing members being connected to means to movethem inside channels determined between adjacent electrodes of oppositepotential during the periods of cleaning the separator.

Other details and features of the invention will "become apparent fromthe description given hereinafter by way of non limiting examples, offorms of embodiment of the invention, with reference to the accompanyingdrawings wherein:

FIG. 1 shows an elevational sectional view along line I--I of FIG. 2' ofan electrostatic separator according to the invention.

FIG. 2 shows a sectional view along line IIII of FIG. 1.

FIG. 3 shows a perspective view of a detail of FIG. 1.

FIG. 4 shows a front view of part of a modification of embodiment of aseparator according to the invention.

FIG. 5 shows a sectional view along line VV of FIG. 4.

The electrostatic separator shown on the drawings comprises a metalvessel 1 with an admission opening 2 and a discharge opening 3 of thegas to be separated.

Inside the vessel are mounted two sets of electrodes: on the one hand,low tension electrodes 4, made from plates taking up nearly the entirewidth of the vessel, and threaded on three pairs of metal stems 5fastened by means of screws 6 on the Walls 7 of the vessel; on the otherhand, high tension electrodes, each comprising two plates 8, 8' inalignment, threaded on stems 9 fastened on insulators 10- carried on thewalls 7. The length of the plates 8, 8 is less than half the length ofthe plates 4 and they are positioned so as to leave between them a freespace 11 and leave uncovered a part 12 of the adjacent plates 4, on theside of the walls of the vessel 1. The plates 4 are kept at the requiredspacing the ones from the others by cylindrical distance pieces 13,threaded on the stems 5; similarly the plates 8, 8' are kept spaced onefrom the other by means of distance pieces 14 threaded on the stems 9. 7

On the rim 16 of each low tension plate 4 directed towards the admission'2 of the vessel, is mounted riderfashion, in sliding contact, a thinmetal channel section 17, the legs of which are bent in direction of theadjacent plates 8, 8" and towards the discharge opening 3, so

as to provide a thin strip 18 projecting outwards on each of the facesof the plates 4.

At a slight distance from the sections 17, each of the faces of theplates 4 carries a second thin metal section with a portion 19 welded onthe plate 4 and a projecting strip 20, inclined parallel to the adjacentstrip 18.

The separator comprises cleansing members for the plates 4, 8, 8- aswell as emitting electrodes 18, '20. These members comprise brushes 21provided with a reciprocal movement in the channels determined each timebetween a plate 4 and the adjacent plates 8, '8'.

Each brush comprises a central stem 22 fastened at the top end thereofby a square 23 to a channel shaped runner 24 mounted so as to slidealong the downstream rim 25 of the plates 4.

Each plate 4 carries indeed two sections 17 in alignment 17, 17, each ofwhich corresponds to one half of the length of the plate; the ends ofthe section 17 are bent at right angles so as provide fins 36. On theside directed towards the wall of the vessel 1, the fins 36 of thesections 17, 17' are seized each time between a U-shaped sustainingcomponent 37 and a small plate 38. Said plate 38 has a central recess 43(FIG. 2) around the emitting channel section 17 and said plate 38 isrigidly connected to the fins 36 and the adjacent face of the sustainingcomponent 37 by means of bolts 44. At the center, the fins 36 adjacentto the sections 17, 17 are pinched between two U-shaped sustainingcomponents 39, 40.

The stem 22 of the brushes 21 provided at the inlet of the channelsdetermined between the plates 4 and the plates 8 is fastened at itsbottom end to the corresponding U-shaped sustaining component 37 whilethe stem 22 of the brushes provided at the inlet of the channelsdetermined between the plates 4- and the plates 8' is fastened to thecorresponding Ushaped sustaining component 39. A handle 27 connected tothe small plates 38 located on the side of the wall 30' and to the endfacing said wall 30 of the runners 24 by means of arms 28 passingthrough ports 29 in the wall 30 of the vessel, permits movement of thebrushes 21, which at rest are aligned outside the said channels in orderto prevent short circuits. In fact, when the handle 27 is actuated, itpulls simultaneously on the runners 24 and on the thin metal emittingchannel section 17, thus the runners 24 and channel section 17 movealong the corresponding rims of the plates together with the brushers21.

When the separator is under tension, preferably in such a manner thatthe positive pole of the high tension source is connected to one end ofone of the stems 9, mounted on one of the insulators .10, so that theplates 8, 8' are at high potential, while the second pole of the tensionsource and the vessel 1 are earthed, so that the plates 4 and the strips18, are at the low potential, an electrostatic field is establishedbetween the electrodes 4 and the electrodes 8, 8 and the rims of thestrips 18, 20 produce a corona effect of electron emission definitelydirected towards the adjacent electrodes 8, 8' and in direction of thearrow 35 which corresponds to the direction of flow of the gas to beseparated, which is forced through the electrostatic separator by meansof a pump, not shown, located at the admission or the outlet of theseparator. Downstream of the zone comprising the sections 17 and 19zone, which is the re-ionization zone of the separator, the electroniccharged dust particles will be deposited on the remaining portion of theelectrodes 8, 8', this zone of the separator being the attracting zone.

Periodically, the tension of the separator is cut out and the plates arecleaned by producing a reciprocal movement of the brushes 21 along therims 16 and of the plates 4 by any appropriate mechanical means.

The form of embodiment shown in the FIGS. 4, 5 relates to anelectrostatic separator of the same type as that described hereinbefore,but wherein the direction of flow of the gas to be separated ishorizontal.

In this case the plates 8 are made from one piece, likewise the sections17 which are mounted in a stationary manner on the rims of the plates 4.

At the top, the vessel is closed by means of a removable cover 4-5,fastened by means of bolts 46 to the side walls 47. Flanges 48 carriedon the walls 47 determine an admission opening 49 and an exhaust opening50 for the gas. Y

The brushes 51 are carried on two arms 53, 54, fastenecl outside thevessel 1, to two angles 55 part of a frame 56 having a centraltransverse member 57 whereon is mounted a cylinder 58 of a hydraulicram, the piston rod 59 thereof is fastened to the cover 45. The lengthof the arms 53 is about equal to the height of the plates 4, so thatwhen the hydraulic ram is actuated, the brushes, normally positioned inthe top part of the vessel, on the outside of the channels determinedeach time between the electrodes 4 and the adjacent electrodes 8, areimpelled with a vertical reciprocal motion in the said channels.

It will be understood that the invention is not limited to the forms ofembodiment described and that many modifications may be introducedtherein without departing from the scope of the present patentapplication.

Thus, more than two emitting electrodes may be provided facing each ofthe electrodes of opposite potential. Thus also the emitting electrodesmay be carried by the insulated plates, which are then connected forpreference to the negative pole of the tension source, the vessel andthe plates which are in electric contact therewith being connected toearth same as the positive pole of the tension source. Thus moreover thecleansing members may be carried out as scrapers mounted in the samemanner as the brushes shown in the drawings.

I claim:

1. An electrostatic separator comprising:

a housing having an'inlet and an outlet with said housing definingtherein a gas flow path from said inlet to said outlet;

laterally spaced parallel electrode plates, said electrode platescomprising a grounded set and an isolated set, alternately positionedacross said housing, parallel to the general direction of the gas flow;

said plates having upstream and downstream rims transversely to thegeneral direction of the gas flow;

channel-shaped thin metal profiles mounted riderfashion on the upstreamrim of the plates of one set of plates;

said channel-shaped profiles having edges projecting downstream towardsthe corresponding adjacent plates of the other set, and means forsupplying high voltage unidirectional current of opposite sign to thegrounded and isolated plates, with the profile carrying plates beingconnected to the negative pole of the high voltage source, whereby theelectric discharge from said projecting edges will charge impurities ofthe gas flow and will deflect them in the direction of the outlet of thehousing.

2. An electrostatic filter as claimed in claim 1 in which at a distancefrom the channel-shaped profiles and parallel therewith a thin metalstrip is attached to each face of the profile carrying plates, saidtrips having edges projecting downstream towards the correspondingadjacent plate of the other set of plates.

3. An electrostatic filter as claimed in claim 1, in which the profilecarrying plates are the grounded ones.

4. An electrostatic filter as claimed in claim 1, in which the nonprofile carrying plates extend beyond the upstream rim of the profilecarrying plates.

5. An electrostatic separator comprising:

a housing having an inlet and an outlet with said housing definingtherein a gas flow path from said inlet to said outlet and defining anattracting zone and a preionization zone situated upstream of saidattracting zone;

two sets of alternately-parallel to the general direction "of the gasflow-arranged, plate-shaped electrodes;

means for supplying high voltage of opposite sign to the electrodes ofeach set;

all the electrodes extending through both of said zones and havingupstream and downstream rims substantially perpendicular to the gas flowpath through the housing;

and channel-shaped thin metal profiles mounted riderfashion on theupstream rim of one set of said electrodes, with said electrodes beingconnected to the negative pole of the high voltage, said channelshapedprofiles having edges projecting downstream towards the correspondingadjacent electrode of the other set, whereby the part of the electrodeswhich for one set carries said profiles and for the other set faces saidprofiles, comprises said ionization zone of the separator and thedownstream part of the electrodes comprises the attracting zone.

6. An electrostatic separator according to claim 5, further comprisingin the preionization zone additional emitting longitudinal thin metalstrips mounted on said negative electrodes, downstream and parallel tosaid channel-shaped profiles, with said strips having edges projectingdownstream towards the corresponding adjacent electrode.

7. An electrostatic separator according to claim 5, in which saidhousing has metallic walls and further including means for mounting saidprofiles carrying plates without insulation on said walls and isolatormeans for mounting said non profile carrying plates on said Walls.

8. An electrostatic separator comprising:

a, housing having an inlet and an outlet with said housing definingtherein a substantially vertical gas flow path from said inlet upwardsto said outlet;

laterally spaced parallel electrode plates defining between each other achannel, said electrode plates comprising a grounded set and an isolatedset alternately positioned across said housing and parallel to thegeneral direction of the gas flow;

said plates having lower-upstream and upper-downstream rims locatedtransversely to the general direction of the gas flow and lateral rimssubstantially perpendicular to said direction;

channel-shaped thin metal profiles mounted riderfashion on the upstreamrim of the plates of one set of plates;

said channel-shaped profiles having edges projecting downstream towardsthe corresponding adjacent plate of the other set, and means forsupplying high voltage unidirectional current of opposite sign to thegrounded and isolated plates with the profile carrying plates beingconnected to the negative pole of the high voltage supplying meanswhereby the electric discharge from said projecting edges will chargeimpurities of the gas flow and deflect said gas flow so that saidimpurities will deposit on the plates of the other set, upstream of partthereof which faces said channel-shaped profile, said separator furthercomprising;

at least one cleansing means arranged in each channel, a center sterncarrying each cleansing means, said stems extending substantiallyparallel to said lateral rims and in a central plane between saidchanel- Cir shaped profiles, runners slidably supported on the upper rimof each second electrode plate, each runner having a pair of bracketsurfaces extending symmetrically in two neighboring channels, the stemof said cleansing means corresponding to the two said channels beingattached at one end thereof to the said runner bracket surfaces,sustaining means for supporting the other end of said stems and forguiding them along the lower rim of the said runner supporting plates,means to reciprocate said runners, and sustaining members along theupper and lower rims of the plates.

9. An electrostatic separator as claimed in claim 8, in

which said sustaining members comprise a channel component bridging saidprofile and rigidly mounted therewith.

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